The present invention relates to rotary regenerative air preheaters. More particularly, the invention relates to apparatus for locating components of an air preheater during the construction thereof.
Many preheater rotors utilize stay plates, rotor shell plates, and rotor angles as structural support and seal support members. Based on requirements of adjoining parts such as baskets, pin racks, peripheral seals and rotor covers, these items must be located very accurately. During construction of conventional air preheaters, the stay plates, rotor shell plates, and rotor angles are individually located in each compartment as that compartment is assembled. The position of each of these items is determined by taking measurements from the rotor post at the top and bottom of each diaphragm plate and snapping a line to mark each location. Once these items are located, they must be tack welded into place until the rotor is fully constructed. Accumulation of tolerances quite often causes problems, requiring removal of tack welds and repositioning of rotor components.
The problems associated with constructing the rotors in the manner described above are aggravated by the fact that a significant portion of such rotors are typically constructed in the field. The number of shop built compartments versus field built compartments varies based on the rotor design and the rotor size. One arrangement, of many, has six 30xc2x0 shop built compartments and six 30xc2x0 field built compartments, with a field built compartment being disposed between each shop built compartment.
Reliance on shop or field personnel to layout the individual components results in errors which are often not discovered until the assembly is complete. These errors require either rework of the assembly or the manufacture of special heat exchange material baskets, pin rack installation material, peripheral seals, and/or rotor covers.
Outage duration is also a major concern when installing new rotors. Laying out the location of the stay plates, shells and rotor angles is very time consuming.
The present invention relates to a method for constructing a rotor of an air preheater, where the rotor comprises a plurality of diaphragm plates, which divide the rotor into a number of wedge-shaped compartments. In addition to the diaphragm plates, each compartment includes compartment components such as a rotor shell plate, a hot end rotor angle, a cold end rotor angle, and one or more stay plates. Each compartment component includes means for locating at least a portion of the component within the compartment. The diaphragm plates are manufactured by marking at least one index location associated with each compartment component on each diaphragm plate blank utilizing a template or other means identifying the index locations and forming an opening at each index location. Each compartment is assembled by positioning a first diaphragm plate adjacent to a second diaphragm plate at an acute angle and locating each compartment component between the adjacent diaphragm plates by engaging the locating means in an associated opening in one of the diaphragm plates. The rotor is assembled by assembling all of the compartments as recited above and then fixedly mounting the compartment components to the diaphragm plates.
In one embodiment, the locating means comprises at least one tab extending from each of the sides of the compartment components. The tab extending from one side of each compartment component is inserted into the associated opening in one of the diaphragm plates and the tab extending from the other side of each compartment component is inserted into the associated opening in the other diaphragm plate to locate the component.
In another embodiment, the locating means comprises a plurality of pins. A first end portion of one of the pins is inserted through one of the openings until a middle mounting portion is disposed within the opening and the first and second end portions extend from the first and second sides of the diaphragm plate, respectively. The pin is then mounted to the diaphragm plate. These steps are repeated until a pin is mounted in predetermined openings in the diaphragm plate. The compartment components are located by positioning each component in engagement with one or more of the pins.
An object of the invention is to provide a simplified, accurate and time saving means to locate stay plates, rotor shell plates and rotor angles in an air preheater.